A computer network is a collection of interconnected computing devices that can exchange data and share resources. In a packet-based network, such as an Ethernet network, the computing devices communicate data by dividing the data into variable-length blocks called packets, which are individually routed across the network from a source device to a destination device. The destination device extracts the data from the packets and assembles the data into its original form.
Certain devices, referred to as routers, maintain routing information representative of a topology of the network. The routers exchange routing information so as to maintain an accurate representation of available routes through the network. A “route” can generally be defined as a path between two locations on the network. Upon receiving an incoming data packet, a router examines information within the packet, often referred to as a “key,” to select an appropriate next hop to which to forward the packet in accordance with the routing information.
In general, service providers, such as an Internet service provider providing network services within the core of the Internet, continue to struggle to meet increasing bandwidth demands. One way to meet increasing bandwidth needs is to use “multi-chassis” routers. A multi-chassis-router is a router in which multiple routing nodes are physically coupled and configured to operate as a single routing node. One example of a multi-chassis router includes multiple line card chassis (LCCs), which include one or more interface cards (IFCs) for sending and receiving packets, and a central switch control chassis (SCC), which provides top-down management of the LCCs. This type of multi-chassis router is often referred to as a single-headed multi-chassis router, i.e., a routing system in which all routing computations are done on a single routing engine that is designated as the master of the routing system. To peer routers on the network, the multi-chassis router appears as a single routing node. Because multi-chassis routers combine resources of multiple routing devices, multi-chassis routers have much higher bandwidth capabilities than standalone routers. For example, the use of multi-chassis routers can simplify and improve routing on a service provider network by consolidating routing functions onto fewer routers.